1. Field of the Invention
This invention is directed to a control valve assembly usable with an oxidation tank and systems and methods for using such a control valve assembly.
2. Related Art
A variety of fluids, including well water, commonly contain oxidizable contaminants, impurities, constituents or the like. For example, well water often contains naturally occurring mineral contaminants. Iron, sulfur, and manganese, which are frequently found in well water, are objectionable in well water and other potable water, as they add undesirable odors and/or taste to the water. These oxidizable constituents may also stain plumbing fixtures and/or corrode and/or clog pipes.
Oxidizable constituents in a fluid are commonly removed from the fluid by entraining an oxygen-containing gas into the fluid and passing the treated fluid through a bed of calcium carbonate or dolomite. This raises the pH level of the fluid and facilitates precipitation of the undesirable oxidizable constituents. The increased pH fluid may then be passed through one or more filter media to remove the precipitated oxidizable constituents. Commonly, the oxygen-containing gas is added to the fluid by passing the fluid through a pipe section of decreasing cross-sectional area with a gas inlet known as a venturi nozzle.
Treatment systems employing venturi nozzles to “aerate” the fluid present certain difficulties in service and operation. If the fluid contains other sediments, strainers are commonly installed upstream of the venturi nozzle to remove the sediment in the fluid that would otherwise obstruct the venturi nozzle. Maintaining the correct differential pressure between the pump and the pressure tank of the system that insures the venturi nozzle operates properly is difficult. Gas introduced upstream of the pressure tank may cause pipes to plug ahead of the pressure tank. The strainer and the venturi nozzle both increase the pressure drop in the fluid system, which may have an adverse effect on the amount of fluid needed to backwash the system. In addition to these maintenance and operation difficulties, the venturi nozzle only operates when the fluid is flowing through the system.
Although it is known to substitute an air pump for a venturi nozzle in a filtration system, such systems remain dependent on the fluid flow in the fluid system to bring fresh oxygen to the fluid. U.S. Pat. No. 5,096,596, which is incorporated herein by reference in its entirety, discloses systems and methods for injecting air or other oxygen-containing gas directly into an air head of an aeration tank, using a controller having a timer to automatically actuate a source of compressed oxygen-rich gas and/or supply an oxygen-containing gas to an oxidation tank at preselected times. U.S. Published Patent Application 2003-0164337 (now allowed) discloses a novel multi-valve control system useable to controllably supply a fresh charge of an oxygen-containing gas to an oxidation tank. The oxygen-containing gas is introduced into a supplied fluid by dispersing or diffusing a spray of droplets of the fluid into a charge of the oxygen-containing gas contained within the oxidation tank. The fluid typically contains one or more oxidizable constituents or contaminants. The mist or spray of droplets absorbs some of the oxygen-containing gas, or at least oxygen from the oxygen-containing gas, from the charge of gas contained within the tank as the fluid falls through the charge of oxygen-containing gas. The oxygen absorbed into the fluid reacts with the oxidizable contaminants or constituents of the fluid, and oxidizes them to form oxide compounds. These oxide compounds typically precipitate out of solution from the fluid and thus can be filtered from the fluid.
As the oxygen content of the oxygen-containing gas is consumed, it is desirable to replace the current charge of oxygen-containing gas with a fresh charge of the oxygen-containing gas. As disclosed in the 337 Published application, this is accomplished by activating the disclosed multi-valve control system. In particular, in the exemplary embodiment disclosed in the 337 Published application, a controlled valve is moved from a first position to a second position. In the first position, the controlled valve connects an interior chamber within a valve assembly of the multi-valve control system to an ambient atmosphere. In the second position, the controlled valve disconnects the interior chamber from the ambient atmosphere and connects the interior chamber to a higher-pressure supply of the oxygen-containing gas.
A second valve is located within the interior chamber. In a first position, the second valve closes off a first flow passage from the interior chamber into the interior of the oxidation tank. In the first position, the second valve also allows a third valve to disconnect a second flow passage out of the interior of the oxidation tank from a drain line. In a second position, the second valve opens the first flow passage between the interior chamber and the interior of the oxidation tank and operates the third valve to connect the second flow passage from the first flow passage to the drain line.
In response to the higher-pressure gas in the interior chamber when the controlled valve is in the second position, the second valve moves from the first position to the second position. This allows a fresh charge of the oxygen-containing gas, which has flowed into the interior chamber from the supply of oxygen containing gas, to flow from the interior chamber through the first flow passage into the interior of the oxidation tank. This fresh charge of the oxygen-containing gas drives the current, stale charge of the oxygen-containing gas, and possibly some of the fluid, from the interior of the oxidation tank out through the second flow path, past the third valve and into the drain line. Consequently, the fresh charge of the oxygen-containing gas replaces the stale charge of the oxygen-containing gas in the interior of the oxidation tank.
Once the fresh charge of oxygen-containing gas is in place in the interior of the oxidation tank, the controlled valve is returned from the second position to the first position. This cuts off the supply of higher-pressure oxygen-containing gas to the interior chamber and re-connects the interior chamber to the ambient atmosphere.
As a result, the higher-pressure oxygen-containing gas within the interior chamber escapes to the ambient atmosphere, and the pressure in the interior chamber drops to the level of the lower-pressure ambient atmosphere. In response, the second valve automatically returns from the second position to the first position, disconnecting the first flow passage from the interior chamber. This also traps the fresh charge of oxygen-containing gas in the interior of the oxidation tank. Additionally, the second valve, as it returns to the first position, allows the third valve to return to its first position where the second flow path is disconnected from the drain line.